The purpose of this project is to contribute to the understanding of hormone action on metabolic processes in normal breast tissue under various conditions and to understand the failure of or aberrant response to hormones by hyper-plastic or neoplastic breast tissue under the same conditions. Among the topics studied are the response of mammary tissue in culture to hormones in terms of nucleic acid, protein, phosphoprotein, sialoglycoprotein, glycoprotein and glycosaminoglycan synthesis. The kinds of proteins and other macromolecules made by mammary tissue in various stages of differentiation during preneoplasia and by neoplastic mammary tissue are being analyzed. Analyses of rodent and human milks, explants and formalin-fixed rodent and human breast tissue are in progress. Of particular interest are the post-translational modifications of proteins which occur during differentiation and neoplasia.